Profiled strainer bars and strainers made from such profiled strainer bars which are also commonly referred to as “bar strainer structure”, are known for example from WO 2008/119548 A2, EP 0 316 570, EP 0 499 154 B1, EP 0 808 941 B1, EP 1 205 227 A1, DE 44 32 842 A1, DE 196 09 316 C2 and EP 0 774 022 B1.
In the strainer according to WO 2011/157529 A1, the strainer bars have respective curvatures upstream and downstream at their slot-forming flanks. These curvatures have radii whose centers are far apart. In any event, they have no common center point.
Profiled strainer bars and strainers made therefrom have an essentially a constant slot width and profile depth across the entire height or longitudinal axis of the strainer or in the Z direction. In the throughput direction or in the Z direction of the strainer, however, there are different requirements for the conditions for implementing the straining and sorting treatment. Thus, for example, the thickening conditions or fiber thickening conditions change, as well as the capacities in the throughput direction of such strainer.
It is thus an object of the invention to provide a profiled strainer bar and a strainer made of such profiled strainer bars, which improve the sorting efficiency, have a low tendency for clogging and produce and achieve higher throughput rates.